Focusing method, imaging device, and unmanned aerial vehicle

ABSTRACT

A focusing method includes determining an initial search direction based on a present position of a lens. The focusing method also includes controlling the lens to perform a focusing process in the initial search direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication No. PCT/CN2016/100130, filed on Sep. 26, 2016, the entirecontents of which are incorporated herein by reference.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

TECHNICAL FIELD

The present disclosure relates to the technology field of imageprocessing and, more particularly, to a focusing method, an imagingdevice, and an unmanned aerial vehicle (UAV).

BACKGROUND

Imaging devices are widely equipped with an auto focus (“AF”) function.In particular, contrast focusing methods have been widely implementedfor auto focus.

A contrast focusing method requires acquisition of at least three framesof images to determine an initial search direction for a focusingprocess. As a result, the time spent for the auto focus process isrelatively long.

SUMMARY

In accordance with the present disclosure, there is provided a focusingmethod. The focusing method includes determining an initial searchdirection based on a present position of a lens. The focusing methodalso includes controlling the lens to perform a focusing process in theinitial search direction.

Also in accordance with the present disclosure, there is provided animaging device. The imaging device includes an imaging assembly and aprocessor. The imaging assembly includes a lens. The processor isconfigured to determine an initial search direction based on a presentposition of the lens. The processor is also configured to control thelens to perform a focusing process in the initial search direction.

In various embodiments of the present disclosure, by determining aninitial search direction based on a present position of the lens, and bycontrolling the lens to perform the focusing process in the initialsearch direction, the disclosed methods and systems do not requireacquisition of at least three frames of images to determine the initialsearch direction. As a result, the speed of auto focus is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

To better describe the technical solutions of the various embodiments ofthe present disclosure, the accompanying drawings showing the variousembodiments will be briefly described. As a person of ordinary skill inthe art would appreciate, the drawings show only some embodiments of thepresent disclosure. Without departing from the scope of the presentdisclosure, those having ordinary skills in the art could derive otherembodiments and drawings based on the disclosed drawings withoutinventive efforts.

FIG. 1 is a schematic diagram of an imaging device according to anexample embodiment.

FIG. 2 is a schematic diagram of an unmanned flight system according toan example embodiment.

FIG. 3 is a flow chart illustrating a focusing method according to anexample embodiment.

FIG. 4 is a plot illustrating a relationship between the object distanceand the image distance according to an example embodiment.

FIG. 5 is a diagram illustrating a method of determining an initialsearch direction according to an example embodiment.

FIG. 6 is a flow chart illustrating a focusing method according toanother example embodiment.

FIG. 7 is a schematic diagram of an imaging device according to anexample embodiment.

FIG. 8 is a schematic diagram of an unmanned aerial vehicle according toan example embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Technical solutions of the present disclosure will be described indetail with reference to the drawings. It will be appreciated that thedescribed embodiments represent some, rather than all, of theembodiments of the present disclosure. Other embodiments conceived orderived by those having ordinary skills in the art based on thedescribed embodiments without inventive efforts should fall within thescope of the present disclosure.

Example embodiments will be described with reference to the accompanyingdrawings, in which the same numbers refer to the same or similarelements unless otherwise specified.

Unless otherwise defined, all the technical and scientific terms usedherein have the same or similar meanings as generally understood by oneof ordinary skill in the art. As described herein, the terms used in thespecification of the present disclosure are intended to describe exampleembodiments, instead of limiting the present disclosure. The term“and/or” used herein includes any suitable combination of one or morerelated items listed.

As used herein, when a first component (or unit, element, member, part,piece) is referred to as “coupled,” “mounted,” “fixed,” “secured” to orwith a second component, it is intended that the first component may bedirectly coupled, mounted, fixed, or secured to or with the secondcomponent, or may be indirectly coupled, mounted, or fixed to or withthe second component via another intermediate component. The terms“coupled,” “mounted,” “fixed,” and “secured” do not necessarily implythat a first component is permanently coupled with a second component.The first component may be detachably coupled with the second componentwhen these terms are used. When a first component is referred to as“connected” to or with a second component, it is intended that the firstcomponent may be directly connected to or with the second component ormay be indirectly connected to or with the second component via anintermediate component. The connection may include mechanical and/orelectrical connections. The connection may be permanent or detachable.The connection may be wired or wireless. When a first component isreferred to as “disposed,” “located,” or “provided” on a secondcomponent, the first component may be directly disposed, located, orprovided on the second component or may be indirectly disposed, located,or provided on the second component via an intermediate component. Theterms “perpendicular,” “horizontal,” “left,” “right,” and similarexpressions used herein are merely intended for description.

Further, when an embodiment illustrated in a drawing shows a singleelement, it is understood that the embodiment may include a plurality ofsuch elements. Likewise, when an embodiment illustrated in a drawingshows a plurality of such elements, it is understood that the embodimentmay include only one such element. The number of elements illustrated inthe drawing is for illustration purposes only, and should not beconstrued as limiting the scope of the embodiment. Moreover, unlessotherwise noted, the embodiments shown in the drawings are not mutuallyexclusive, and they may be combined in any suitable manner. For example,elements shown in one embodiment but not another embodiment maynevertheless be included in the other embodiment.

First, the structural configuration of an imaging device 100 in orthrough which the disclosed focusing method may be implemented will bedescribed below with reference to FIGS. 1 and 2.

FIG. 1 is a schematic diagram of the imaging device 100 according to anembodiment of the present disclosure. As shown in FIG. 1, the imagingdevice 100 includes an imaging assembly 110 and a processor 120.

In some embodiments, the imaging assembly 110 may include a lens, suchas a focusing lens, which may be driven by a motor to perform an autofocus process. In some embodiments, the imaging assembly 110 may includeany suitable device, unit, or component configured to capture images,such as cameras.

In some embodiments, the imaging assembly 110 may communicate with theprocessor 120 through a wired or wireless connection. The imagingassembly 110 may receive control signals or commands from the processor120. The imaging assembly 110 may adjust the focal length based on thecontrol signals.

Without limiting the scope of the present disclosure, in someembodiments, the imaging assembly 110 may include a charge-coupleddevice (“CCD”). The CCD may also be referred to as a CCD imaging sensoror a CCD imaging controller. A CCD is a semiconductor device that canconvert optical images into electrical signals. The photosensitivesubstance embedded in the CCD is referred to as pixels. The more thepixels on the CCD, the higher the resolution of the captured images. CCDoperates like a negative, except that the CCD converts optical signalsinto electrical charge signals. On a CCD, there may be arrays ofphotodiodes, which can sense light, and convert the light into anelectrical signal. The electrical signal is then sampled, amplified, andconverted through an analog-to-digital (AD) converter to become digitalimage signals.

Without limiting the scope of the present disclosure, in someembodiments, the imaging assembly 110 may include a complementary metaloxide semiconductor (“CMOS”). CMOS is a widely used material formanufacturing integrated circuit chips. CMOS manufacturing processeshave also been used to manufacture photosensitive components for digitalimaging devices. The principles of operation for converting opticalsignals into electrical signals in the CCD imaging sensors and CMOSimaging sensors are the same. The main difference between the CCDimaging sensors and the CMOS imaging sensors lies in the signal outputprocess. For a CCD, signals are read out or output from only one (or afew) output node(s). As a result, the signals output from a CCD haveexcellent consistency. For a CMOS chip, every pixel has its own signalamplifier. Every pixel performs a charge-voltage conversion. As aresult, the consistency in the signals output from the CMOS chip is low.For a CCD, in order to output an entire frame of an image signal, thesignal transmission bandwidth of an output amplifier need to be large.Whereas in the CMOS chip, the signal transmission bandwidth of anamplifier associated with each pixel is low, which can significantlyreduce the power consumption of the chip. This is the one of the mainreasons why the CMOS chip consumes less power than the CCD chip.However, although the power consumption is low, inconsistency inmillions of amplifiers can cause much higher noise level. This is anadvantage of the CMOS as compared to CCD.

The above discussed examples of the imaging assembly 110 are forillustrative purposes only, and the present disclosure is not limited tothese examples. Other imaging assembly that can provide auto focus alsofall within the scope of the present disclosure.

In some embodiments, the processor 120 and the imaging assembly 110 arecommunicatively coupled with one another through a wired or wirelessconnection, and can communicate with each other. The processor 120 mayobtain or acquire information relating to a present position of thefocusing lens of the imaging assembly 110. The processor 120 maydetermine an initial search direction based on the present position ofthe focusing lens. In some embodiments, the processor 120 may alsocontrol the focusing lens to perform a focusing process in the initialsearch direction.

In some embodiments, the processor 120 may be a central processing unit(“CPU”). In some embodiments, the processor 120 may be other generalpurpose processor, a digital signal processor (“DSP”), an ApplicationSpecific Integrated Circuit (“ASIC”), a field programmable gate array(‘FPGA”). In some embodiments, the processor 120 may be otherprogrammable logic devices, gates, or transistor logic devices, gatehardware assembly, etc. In some embodiments, the processor 120 may be amicroprocessor, or any other regular processor. In some embodiments, theFPGA may be developed based on other programmable components, such asprogrammable array logic (“PAL”), generic array logic (“GAL”), complexprogrammable logic device (“CPLD”). FPGA is a semi-custom circuit in theASIC technical field. FPGA can not only address disadvantages associatedwith custom-circuits, but also resolve issues associated with thelimitation on the number of programmable components or circuits. Basedon applications, a system designer may couple the internal logiccomponents of the FPGA through programmable connections, as if anexperimental circuit board is placed in a chip. A complete FPGA productout of the manufacturing facility can be customized by a designer byaltering the logic components and connections. Thus, FPGA can be used toimplement logic functions in various devices.

In some embodiments, various components of the imaging device 100 may beintegrated in a single device. For example, the single device may be acamera, a camcorder, or any other smart terminals equipped with imagingfunctions, such as cell phones, tablets, or laptops, etc.

In some embodiments, various components of the imaging device 100 may beprovided in different separate devices. For example, the imagingassembly 110 may be provided in an unmanned aerial vehicle (“UAV”). Theprocessor 120 may be provided in the UAV or may be provided in a controlterminal, such as a remote control or a smart terminal installed withcontrol software. The present disclosure does not limit the type ofdevices.

UAVs have been widely used in civil applications. For example, UAVs havebeen used for agriculture, aerial photography, wild fire surveillance,etc. Civil applications of the UAVs appear to be a trend for the future.

In some embodiments, a UAV may include a carrier to carry a payload forimplementing a task. For example, in aerial photography, a UAV mayinclude a gimbal to carry an imaging device, such as the imagingassembly 110 of the present disclosure. FIG. 2 is schematic diagram ofan unmanned flight system 200. For simplicity, the followingdescriptions use a rotorcraft as an example of the UAV for discussion.

In some embodiments, the unmanned flight system 200 includes a UAV 210,a gimbal 220, a display device 230, and an operating device 240. The UAV210 includes a propulsion system 250, a flight control system 260, aframe 270, and a focusing processor. The UAV 210 may communicatewirelessly with the operating device 240 and the display device 230.

In some embodiments, the frame 270 may include a body and supportinglegs (also referred to as landing gears or landing legs). The body mayinclude a central frame and one or more arms coupled with the centralframe. The one or more arms may radially extend from the central frame.The supporting legs may be coupled with the body, and may support theUAV 210 during landing or while landed.

In some embodiments, the propulsion system 250 includes an electricalspeed control (“ESC”) 251, one or more propellers, and one or moremotors 252 corresponding to the one or more propellers. In someembodiments, the motor 252 and the propeller 253 may be mounted on eachcorresponding arm. The ESC 251 may be configured to receive drivingsignals generated by the flight control system 260. The ESC 251 maysupply an electrical current to the motor 252 based on the drivingsignals, and may control the speed and rotation direction of the motor252. In some embodiments, the motor 252 may drive the propeller 253 torotate, thereby providing propulsion forces to the UAV 210, which enablethe UAV 210 to move in one or more degrees of freedom. In someembodiments, the UAV 210 may rotate around one or more axes of rotation.For example, the axes of rotation may include a roll-axis, a yaw-axis,and a pitch-axis. In some embodiments, the motor 252 may be a directcurrent motor or an alternating current motor. In some embodiments, themotor 252 may be a brushless motor or a brushed motor.

In some embodiments, the flight control system 260 includes a flightcontroller 261 and a sensor system 262. The sensor system 262 mayinclude various sensors to detect, measure, obtain, sense, or acquireinformation or data relating to the altitude of the UAV 210. Theinformation includes the position information and status information ofthe UAV 210, such as the three-dimensional position, three-dimensionalangle, three-dimensional velocity, three-dimensional acceleration, andthree-dimensional angular velocity, etc. The sensor system 262 mayinclude at least one of a gyroscope, a digital compass, an inertialmeasurement unit (“IMU”), a vision sensor, a global positioning system(“GPS”) sensor, or a barometer. In some embodiments, the flightcontroller 261 is configured to control the flight of the UAV 210. Forexample, the flight controller 261 may control the flight of the UAV 210based on the information relating to the altitude of the UAV 210 thatmay be acquired by the sensor system 262. In some embodiments, theflight controller 261 may control the flight of the UAV 210 based onpre-programmed instructions, codes, or commands. In some embodiments,the flight controller 261 may control the flight of the UAV 210 byresponding to one or more command signals received from the operatingdevice 240.

In some embodiments, the gimbal 220 includes at least one bracket 221for supporting or carrying the imaging assembly 223. The gimbal 220 alsoincludes at least one motor 222 configured to drive the at least onebracket 221 to rotate. Each motor 222 may drive a corresponding bracket221 to rotate. In some embodiments, the imaging assembly 223 may be anembodiment of the imaging assembly 110 discussed above, and may havesimilar or the same structures and functions.

In some embodiments, through the ESC 224 and the motor 222, the flightcontroller 261 may control the gimbal 220 to rotate, thereby causing theimaging assembly 223 to rotate. In some embodiments, the gimbal 220 mayinclude a controller configured to control the ESC 224 and the motor222, thereby controlling the rotation of the imaging assembly 223. Insome embodiments, the gimbal 220 may be independent from the UAV 210(e.g., being detachable from the UAV 210 or being separately operated orcontrolled from the operations of the UAV 210). In some embodiments, thegimbal 220 may be an integral part of the UAV 210. In some embodiments,the motor 222 may be a direct current motor or an alternating currentmotor. In some embodiments, the motor 222 may be a brushless motor or abrushed motor. In some embodiments, the payload may be placed on a topportion of the UAV 210 or attached to a lower portion of the UAV 210.

Although not shown in the figures, in some embodiments, the unmannedflight system 200 may include a focusing processor. The focusingprocessor may be programmed or configured to control the imagingassembly 223 to perform a focusing process. The structure and functionof the focusing processor may be similar to or the same as the processor120 discussed above. In some embodiments, the focusing processor may beprovided in the UAV 210, or may be provided in the operating device 240or the display device 230. The present disclosure does not limit thelocation of the focusing processor.

In some embodiments, the display device 230 may be located on the groundside of the unmanned flight system 200. The display device 230 maycommunicate with the UAV 210 through wireless communication. The displaydevice 230 may be configured to display the information relating to thealtitude of the UAV 210, as well as images captured by the imagingassembly 223. In some embodiments, the display device 230 may be anindependent device (e.g., independent of operating device 240), or maybe integral with the operating device 240.

In some embodiments, the operating device 240 may be located on theground side of the unmanned flight system 200. The operating device 240may communicate with the UAV 210 through wireless communication. Theoperating device 240 may send signals to the UAV 210 to remotely operateor control the UAV 210. The operating device 240 may be any suitableoperating device, such as a remote control or a smart terminal installedwith an UAV application, such as a smart phone, a tablet, etc. Accordingto the present disclosure, the operating device 240 may receive inputfrom a user through a wheel, a button, a key, a joystick, or a userinterface (“UI”), and may control the UAV 210 based on the input fromthe user.

In some embodiments, the focusing processor may be a designatedprocessor for performing the focusing processes. In some embodiments,functions of the focusing processor may be implemented in other devicesof the unmanned flight system 200, such as a processor included in theoperating device 240, or a processor included in the imaging assembly223. The present disclosure does not limit the manner in which thefocusing processor or its functions are implemented.

It is understood that the names of the various components of theunmanned flight system 200 are for identification purposes only, andshould not be construed to limit the scope of the present disclosure.

The actions and the interactions between the imaging assembly 223 and aprocessor (e.g., any processor disclosed herein including the focusingprocessor) will be explained below.

According to the present disclosure, the focusing method is a contrastfocusing method. The contrast focusing method realizes auto focus bydetecting edges of a contour of an object in the captured image. Theclearer the contour of the object in the captured image, the greater thegradient of the brightness of the image. In other words, the contrastbetween the edge imaging areas and the background is greater.Conversely, poorly focused images have blurry contour edges, reducedgradient in the brightness or reduced contrast. The poorer the focus,the lower the contrast.

FIG. 3 is a flow chart illustrating a focusing method 300 according tothe present disclosure. As shown in FIG. 3, the focusing method includesstep S310 and step S320, which may be executed by the processor (e.g.,the focusing processor). In step S310, the processor determines aninitial search direction based on a present position of a lens, such asa focusing lens. In step S320, the processor controls the lens, such asthe focusing lens to perform a focusing process in the initial searchdirection.

According to the focusing method of the present disclosure, theprocessor determines the initial search direction based on the presentposition of the focusing lens, thereby reducing the time spent indetermining the initial search direction, and improving the speed ofauto focus.

According to embodiments of the present disclosure, in the process ofauto focusing, the focusing lens may move back and forth along theoptical axis. The processor may determine the present position of thefocusing lens on the optical axis, and then determine the initial searchdirection based on the present position of the focusing lens.

According to embodiments of the present disclosure, the processor maydetermine the present position of the focusing lens based on informationrelating to a stroke of a driving device configured to drive thefocusing lens to move.

For example, a predetermined relationship between the stroke of thedriving device and the position of the focusing lens may be specified.When the processor determines the stroke of the driving device, theprocessor may determine the present position of the focusing lens basedon the stroke and the predetermined relationship between the stroke ofthe driving device and the position of the focusing lens.

According to embodiments of the present disclosure, as non-limitingexamples, the driving device may be a focus motor. The focus motor maybe a voice coil motor (“VCM”) that may include a coil, a magnetsassembly, and resilient brackets. The coil may be mounted to the magnetsassembly through two resilient brackets sandwiching the magnetsassembly. When an electrical current is supplied to the coil, a magneticfield is generated by the coil, which interacts with the magnetsassembly. As a result, the coil may move relative to the magnetsassembly, causing the focusing lens to move along the optical axis. Whenthe supply of the electrical current is stopped, the coil moves backunder the spring force of the resilient brackets, thereby realizing autofocusing. The processor 120 may generate instructions and/or commandsignals to control the supply of the electrical current to the coil.

According to embodiments of the present disclosure, as non-limitingexamples, the focus motor may be an ultrasonic motor including a statorthat has a ring-shaped bottom part, and a rotor that has a ring shape.The ultrasonic motor converts vibration caused by the ultrasonicfrequency wave into rotating energy. When an electrical current issupplied to a piezoelectric component of the ring-shaped bottom part ofthe stator, the stator may vibrate at an amplitude of 0.001 mm at a highfrequency of about 30 kHz. As a result, a flexural traveling wave isgenerated at the contacting interface between the bottom part of thestator and the rotor. The frictional force generated by the flexuraltraveling wave causes the rotor to rotate, thereby causing the focusinglens to move along the optical axis.

In step S310, the processor determines the initial search directionbased on the relationship between the present position of the focusinglens and the reference position.

Alternatively, in some embodiments, the processor may determine theinitial search direction based on a relationship between the presentposition of the focusing lens and a reference position range.

In some embodiments, the reference position or the reference positionrange may be a specific position or a specific position range pre-set bya manufacturer or a user.

In some embodiments, the reference position or the reference positionrange may be determined by the processor based on the focal length ofthe focusing lens.

For example, the processor may determine the reference position or thereference position range based on the focal length of the focusing lens,and a predetermined relationship between the focal length of thefocusing lens and reference positions or reference position ranges,which may be pre-set by the manufacturer or the user.

In some embodiments, the processor may determine the reference positionor reference position range based on the following relationship:1/f=1/v+1/u, where f is the focal length of the focusing lens, u is theobject distance, and v is the image distance. Typically, the focallength f is at the level of millimeter (mm). Based on this relationship,when the image distance is greater than a predetermined distance v0, anychange in the image distance may cause only a small change in the objectdistance. Within the predetermined distance v0, any change in the imagedistance may cause a relatively significant change in the objectdistance. As shown in the example relationship between the objectdistance and the image distance illustrated in FIG. 4, when the imagedistance changes in a range within 110 mm, any change in the imagedistance may cause a large change in the object distance. When the imagedistance changes in a range beyond 110 mm (e.g., greater than 110 mm),any change in the image distance may only cause a small change in theobject distance.

As such, the processor may determine one or more reference position orreference position range based on the relationship between the objectdistance and the image distance. As a non-limiting example, the numberof reference position may be one. Corresponding to the one referenceposition, the focusing lens may have a first object distance. Thefocusing lens may have a second object distance at a focusing positionin a proximal range. A difference between the first object distance andthe second object distance may be smaller than or equal to a firstpredetermined value. An initial focusing position refers to a positionwhere the focusing lens is located when the object distance is infinity.A distance between the focusing position in the proximal range and theinitial focusing position is the total stroke of the focusing lens.

According to embodiments of the present disclosure, as non-limitingexamples, as shown in FIG. 5, when the total stroke of the focusing lensis Vt, the distance between the reference position and the initialfocusing position is ¼ *Vt. For the convenience of description, theinitial focusing position is marked or treated as the 0 position, thestroke ranging from 0 to ¼ *Vt is referred to as a distal range, and theremaining part of the stroke (e.g., ¼ *Vt to Vt) is referred to as aproximal range. The total stroke Vt may be determined based on thestructure of the focusing lens. In other words, the total stroke may befixed or constant for a focusing lens.

According to embodiments of the present disclosure, when the processordetermines the initial search direction, if the processor determinesthat the present position of the focusing lens is within the distalrange, or if the focusing lens is located on a side where the referenceposition is close to the initial focusing position, the processor maydetermine that the initial search direction is a direction in which theinitial focusing position faces or points to the reference position. Theprocessor may control the focusing lens to perform a focusing process inthe initial search direction starting from the present position of thefocusing lens.

In some embodiments, as shown in FIG. 5, if the processor determinesthat the present position of the focusing lens is within the distalrange, or if the focusing lens is located on a side where the referenceposition is close to or adjacent the initial focusing position, theprocessor may determine the initial search direction as a direction inwhich the initial focusing position faces or points to the referenceposition. The processor may control the focusing lens to move to theinitial focusing position, and to perform a focusing process in theinitial search direction starting from the initial focusing position. Asa result, the disclosed embodiments can improve auto focusing speed fordistant objects.

In some embodiments, when the processor determines the initial searchdirection, if the present position of the focusing lens is within theproximal range, or if the focusing lens is located on a side where thereference position is distant from the initial focusing position, theprocessor may determine the initial search direction as a direction inwhich the reference position faces or points to the initial focusingposition. The processor may control the focusing lens to perform afocusing process in the initial search direction starting from thepresent position.

FIG. 6 illustrates a focusing method 600 that may be performed by theprocessor through controlling the focusing lens, after the processordetermines the initial search direction. As shown in FIG. 6, thefocusing method 600 includes steps S610-S630.

In step S610, the processor controls the lens, such as the focusing lensto perform a rough search in the initial search direction.

A step size for the rough search may be pre-set by the manufacturer orthe user. In some embodiments, when the processor controls the focusinglens to perform the rough search in the initial search direction basedon the step size, the processor may terminate the rough search when thecontrast reduces in at least three consecutive frames of images renderedin the search.

In step S620, the processor controls the lens, such as the focusing lensto perform a fine search in a direction opposite the initial searchdirection, to determine the focusing position.

In some embodiments, a step size for the fine search may be pre-set bythe manufacturer or the user. When the processor controls the focusinglens to perform the fine search based on the step size for the finesearch in the direction opposite the initial search direction, theprocessor may terminate the fine search when the contrast reduces in atleast three consecutive frames of images rendered in the search. Throughthe rough search and the fine search, the processor may determine aposition at which the rendered image has the greatest contrast, i.e.,the focusing position.

In step S630, the processor controls the lens, such as the focusing lensto move to the focusing position.

According to the embodiments of the present disclosure, the processormay determine an object distance between the object of imaging and thefocusing lens. The processor may determine a method for focusing basedon the object distance. As non-limiting examples, when the processordetermine that the object distance between the object of imaging and thefocusing lens is greater than or equal to a second predetermined value,the processor may implement the disclosed focusing method(s).

In some embodiments, the second predetermined value may be pre-set bythe manufacturer or the user. For example, the second predeterminedvalue may be 300 meters. The present disclosure does not limit theobject distance between the object of imaging and the focusing lens.

The disclosed methods and systems can reduce the auto focus time forimaging distant objects. In addition, the disclosed methods and systemscan alleviate the breathing phenomenon that may occur in the focusingprocess.

With the disclosed methods, devices, or systems, the initial searchdirection may be determined based on the present position of thefocusing lens, thereby reducing the time spent in determining theinitial search direction, which can improve the speed of auto focus.

The disclosed focusing methods, devices, or systems may be implementedat least in part by a computer. The computer may include a hardwarelayer, an operation system layer running on the hardware layer, and anapplication layer running on the operation system layer. The hardwarelayer may include a central processing unit (“CPU”), a memory managementunit (“MMU”), and a storage device (e.g., memory), etc. The operationsystem may be a system that can run one or more processes, such as aLinux operation system, a Unix operation system, an Android operationsystem, an iOS operation system, or a Windows operation system. Theapplication layer may include at least one of an internet browser, acontact application, a word processing application, an instant messagingapplication, etc. In some embodiments, the computer may be a handhelddevice, such as a smart phone, or a personal computer. The presentdisclosure does not limit the type of the computer, as long as thecomputer is equipped with suitable hardware and software to execute theinstructions or codes that implement the disclosed focusing methods.

Various aspects or features of the present disclosure may be implementedas methods or devices, or may be implemented through programming, or maybe implemented as products of engineering. The term “product” used inthe present disclosure encompasses any computer program that may be readfrom any non-transitory computer-readable medium, device, or apparatus.For example, the computer-readable medium may include, but not belimited to, magnetic storage device (e.g., hard disk, soft disk, ortape, etc.), optical disc (e.g., compact disc (“CD”), compressed drive,digital versatile disc (“DVD”), etc.), smart card, flash drive (e.g.,erasable programmable read-only memory (“EPROM”), card, stick, or keydrive, etc.). Moreover, the various storage medium or device disclosedherein may include one or more devices configured to store information,data, signal, etc. The various storage medium disclosed herein mayinclude any other computer-readable media. The term “computer-readablemedium” may include, but not be limited to, wireless channels and othermedia that may store, include, carry commands and/or data.

The embodiments of the disclosed focusing methods are described above.The embodiments of the disclosed imaging device will be described below.

FIG. 7 is a schematic diagram of an imaging device. As shown in FIG. 7,an imaging device 10 includes a determination processor 11 configured orprogrammed to determine an initial search direction based on informationrelating to the present position of the focusing lens. The imagingdevice 10 also includes a control processor 12 configured or programmedto control the focusing lens to perform a focusing process in theinitial search direction.

The disclosed imaging device of the present disclosure determines theinitial search direction based on the present position of the focusinglens, thereby reducing the time spent in determining the initial searchdirection. As a result, the auto focus speed can be improved.

In some embodiments, the determination processor may be configured orprogrammed to determine the present position of the focusing lens basedon information relating to the stroke of the driving device. The drivingdevice may be configured to drive the focusing lens to move along anoptical axis.

In some embodiments, the determination processor 11 may be configured orprogrammed to determine the initial search direction based on arelationship between the present position of the focusing lens and areference position.

In some embodiments, the determination processor 11 may be configured orprogrammed to determine the reference position.

In some embodiments, the determination processor 11 may be configured orprogrammed to determine the reference position based on predeterminedinformation relating to the reference position.

In some embodiments, the determination processor 11 may be configured orprogrammed to determine the reference position based on the focal lengthof the focusing lens.

In some embodiments, the determination processor 11 may be configured orprogrammed to determine the reference position based on a relationshipbetween the focal length, the object distance, and the image distance ofthe focusing lens.

In some embodiments, the number of reference position is one or morethan one.

In some embodiments, the number of reference position is one. In someembodiments, a difference between a first object distance and a secondobject distance corresponding to the focusing lens at the referenceposition is smaller than or equal to a first predetermined value. Insome embodiments, the second object distance is an object distancecorresponding to a focusing position of the focusing lens in a proximalrange. In some embodiments, an object distance corresponding to thefocusing lens at an initial focusing position is infinity. In someembodiments, a distance between the focusing position in the proximalrange and the initial focusing position equals to a total stroke of thefocusing lens.

In some embodiments, the determination processor 11 may be configured orprogrammed to, when determining that the present position is on a firstside of the reference position, determine the initial search directionas a first direction. The first side of the reference position is a sidethat is adjacent the initial focusing position, and the first directionis a direction in which the initial focusing position faces or points tothe reference position.

In some embodiments, the control processor 12 may be configured orprogrammed to control the focusing lens to move to the initial focusingposition, and to control the focusing lens to perform the focusingprocess in the initial search direction starting from the initialfocusing position.

In some embodiments, the determination processor 11 may be configured orprogrammed to, when determining that the present position is on a secondside of the reference position, determine the initial search directionas a second direction. The second side of the reference position is aside that is distant from the initial focusing position. The seconddirection is a direction in which the reference position faces or pointsto the initial focusing position.

In some embodiments, the control processor 12 may be configured orprogrammed to control the focusing lens to perform the focusing processin the initial search direction starting from the present position.

In some embodiments, the total stroke of the focusing lens is four timesof a distance between the reference position and the initial focusingposition.

In some embodiments, the control processor 12 may be configured orprogrammed to determine that an object distance between the object ofimaging and the focusing lens is greater than or equal to a secondpredetermined value.

Descriptions of the imaging device may refer to the descriptions of thecorresponding focusing method 300 discussed above. Various modules,components, devices, and units included in the imaging device can beused, operated, programmed, or configured to implement one or more stepsof the method 300.

According to various embodiments of the present disclosure, thedisclosed imaging device determines the initial search direction basedon the present position of the focusing lens, thereby reducing the timespent in determining the initial search direction. As a result, thespeed of auto focus is improved.

FIG. 8 is a schematic diagram of a UAV according to an embodiment of thepresent disclosure. As shown in FIG. 8, the UAV 20 includes a processor21 and a storage device 22. The processor 21 may be operably coupledwith the storage device 22 through a data communication bus 23. Thestorage device 22 may store commands, codes, or instructions executableby the processor 21 to perform the methods disclosed herein, includingthe method 300.

A person having ordinary skill in the art can appreciate that when thedescription mentions “an embodiment” or “an example,” it means thatcharacteristics, structures, or features related to the embodiment orexample are included in at least one embodiment or example of thepresent disclosure. Thus, when the description uses “in an embodiment”or “in an example” or similar terms, it does not necessarily mean thesame embodiment. Various characteristics, structures, or features ofvarious embodiments may be combined in a suitable manner. Variouscharacteristics, structures, or features of one embodiment may beincorporated in another embodiment.

A person having ordinary skill in the art can appreciate that thereference numbers for the steps of the methods does not necessarilyindicate the sequence of execution of the steps. The sequence forexecuting the various steps is to be determined by the functions of thesteps and the internal logic between the steps. The example sequenceshown in the flow charts or discussed in the descriptions should not beconstrued as limiting the scope of the present disclosure.

A person having ordinary skill in the art can appreciate that when thedescription refers to “B corresponding to A,” it means that B is relatedto A, and B can be determined based on A. It should be understood thatwhen B can be determined based on A, it does not necessarily mean that Bcan only be determined based on A. B may be determined based on A and/orother information.

A person having ordinary skill in the art can appreciate that when theterm “and/or” is used, the term describes a relationship between relateditems. The term “and/or” means three relationships may exist between therelated items. For example, A and/or B can mean A only, A and B, and Bonly. The symbol “/” means “or” between the related items separated bythe symbol.

A person having ordinary skill in the art can appreciate that part orall of the above disclosed methods and processes may be implementedusing related electrical hardware, or a combination of electricalhardware and computer software that may control the electrical hardware.Whether the implementation is through hardware or software is to bedetermined based on specific application and design constraints. Aperson of ordinary skill in the art may use different methods fordifferent applications. Such implementations fall within the scope ofthe present disclosure.

A person having ordinary skill in the art can appreciate thatdescriptions of the functions and operations of the system, device, andunit can refer to the descriptions of the disclosed methods.

A person having ordinary skill in the art can appreciate that thevarious system, device, and method illustrated in the exampleembodiments may be implemented in other ways. For example, the disclosedembodiments for the device are for illustrative purpose only. Anydivision of the units are logic divisions. Actual implementation may useother division methods. For example, multiple units or components may becombined, or may be integrated into another system, or some features maybe omitted or not executed. Further, couplings, direct couplings, orcommunication connections may be implemented using interfaces. Theindirect couplings or communication connections between devices or unitsor components may be electrical, mechanical, or any other suitable type.

In the descriptions, when a unit or component is described as a separateunit or component, the separation may or may not be physical separation.The unit or component may or may not be a physical unit or component.The separate units or components may be located at a same place, or maybe distributed at various nodes of a grid or network. The actualconfiguration or distribution of the units or components may be selectedor designed based on actual need of applications.

Various functional units or components may be integrated in a singleprocessing unit, or may exist as separate physical units or components.In some embodiments, two or more units or components may be integratedin a single unit or component.

The computer program instructions may be stored in a non-transitorycomputer-readable storage medium. When the computer program instructionsare executed by a processor or controller, method performed by theprocessor or controller may include the above disclosed methods orprocesses. The non-transitory computer-readable storage medium can beany medium that can store program codes, for example, a magnetic disk,an optical disk, a read-only memory (ROM), or a random access memory(RAM), etc.

Other embodiments of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the embodiments disclosed herein. It is intended that thespecification and examples be considered as example only and not tolimit the scope of the present disclosure, with a true scope and spiritof the invention being indicated by the following claims. Variations orequivalents derived from the disclosed embodiments also fall within thescope of the present disclosure.

What is claimed is:
 1. A focusing method, comprising: determining aninitial search direction based on a present position of a lens; andcontrolling the lens to perform a focusing process in the initial searchdirection.
 2. The focusing method of claim 1, further comprising:determining the present position of the lens based on informationrelating to a stroke of a driving device, the driving device beingconfigured to drive the lens to move, wherein determining the initialsearch direction based on the present position of the lens comprises:determining the initial search direction based on a relationship betweenthe present position of the lens and a reference position.
 3. Thefocusing method of claim 2, further comprising: determining thereference position based on at least one of predetermined informationrelating to the reference position, a focal length of the lens, or arelationship between the focal length, an object distance, and an imagedistance of the lens.
 4. The focusing method of claim 3, wherein anumber of the reference position is one or more than one.
 5. Thefocusing method of claim 4, wherein the number of the reference positionis one, wherein a difference between a first object distance and asecond object distance corresponding to the lens at the referenceposition is smaller than or equal to a first predetermined value,wherein the second object distance is an object distance correspondingto a focusing position of the lens in a proximal range, wherein anobject distance corresponding to the lens at an initial focusingposition is infinity, and wherein a distance between the focusingposition in the proximal range and the initial focusing position equalsto a total stroke of the lens.
 6. The focusing method of claim 5,wherein determining the initial search direction based on therelationship between the present position of the lens and the referenceposition comprises: when determining that the present position is on afirst side of the reference position, determining the initial searchdirection as a first direction, wherein the first side of the referenceposition is a side that is adjacent the initial focusing position, andthe first direction is a direction in which the initial focusingposition points to the reference position.
 7. The focusing method ofclaim 6, wherein controlling the lens to perform the focusing process inthe initial search direction comprises: controlling the lens to move tothe initial focusing position; and controlling the lens to perform thefocusing process in the initial search direction starting from theinitial focusing position.
 8. The focusing method of claim 6, whereindetermining the initial search direction based on the relationshipbetween the present position of the lens and the reference positioncomprises: when determining that the present position is on a secondside of the reference position, determining the initial search directionas a second direction, wherein the second side of the reference positionis a side that is distant from the initial focusing position, andwherein the second direction is a direction in which the referenceposition points to the initial focusing position.
 9. The focusing methodof claim 8, wherein controlling the lens to perform the focusing processin the initial search direction comprises: controlling the lens toperform the focusing process in the initial search direction startingfrom the present position.
 10. The focusing method of claim 5, whereinthe total stroke of the lens is four times of a distance between thereference position and the initial focusing position.
 11. The focusingmethod of claim 1, further comprising: prior to determining the initialsearch direction based on the present position of the lens, determiningthat an object distance between the object of imaging and the lens isgreater than or equal to a second predetermined value.
 12. An imagingdevice, comprising: an imaging assembly; and a processor, wherein theimaging assembly comprises a lens, and wherein the processor isconfigured to: determine an initial search direction based on a presentposition of the lens; and control the lens to perform a focusing processin the initial search direction.
 13. The imaging device of claim 12,wherein the processor is further configured to: determine the presentposition of the lens based on information relating to a stroke of adriving device, the driving device being configured to drive the lens tomove; and determine the initial search direction based on a relationshipbetween the present position of the lens and a reference position. 14.The imaging device of claim 13, wherein the processor is furtherconfigured to: determine the reference position based on at least one ofpredetermined information relating to the reference position, a focallength of the lens, or a relationship between the focal length, anobject distance, and an image distance.
 15. The imaging device of claim14, wherein a number of the reference position is one or more than one.16. The imaging device of claim 15, wherein the number of the referenceposition is one, wherein a difference between a first object distanceand a second object distance corresponding to the lens at the referenceposition is smaller than or equal to a first predetermined value,wherein the second object distance is an object distance correspondingto a focusing position of the lens in a proximal range, wherein anobject distance corresponding to the lens at an initial focusingposition is infinity, and wherein a distance between the focusingposition in the proximal range and the initial focusing position equalsto a total stroke of the lens.
 17. The imaging device of claim 16,wherein the processor is further configured to: when determining thatthe present position is on a first side of the reference position,determine the initial search direction as a first direction, wherein thefirst side of the reference position is a side that is adjacent theinitial focusing position, and the first direction is a direction inwhich the initial focusing position points to the reference position.18. The imaging device of claim 17, wherein the processor is furtherconfigured to: control the lens to move to the initial focusingposition; and control the lens to perform the focusing process in theinitial search direction starting from the initial focusing position.19. The imaging device of claim 16, wherein the processor is furtherconfigured to: when determining that the present position is on a secondside of the reference position, determine the initial search directionas a second direction, wherein the second side of the reference positionis a side that is distant from the initial focusing position, andwherein the second direction is a direction in which the referenceposition points to the initial focusing position.
 20. The imaging deviceof claim 19, wherein the processor is further configured to: control thelens to perform the focusing process in the initial search directionstarting from the present position.
 21. The imaging device of claim 16,wherein the total stroke of the lens is four times of a distance betweenthe reference position and the initial focusing position, and whereinprior to determining the initial search direction based on the presentposition of the lens, the processor is further configured to: determinethat an object distance between the object of imaging and the lens isgreater than or equal to a second predetermined value.